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Greenhoue Ventilation: Negative Air Pressure and Passive Systems

With negative air systems, warm air is sucked out with exhaust fans - air intake is through shutters. Sizing of equipment will depend upon the greenhouse dimensions, the season of the year, the crop and the transpiration rate of the crop.

Passive systems use roof vents and wall openings; air flow through a vent can either be up (warm air rising) or down (cold air dropping). Conditions at any given moment will determine the direction.

Outside wind and interior air circulation (typically horizontal air flow, HAF) will influence the performance of both negative air and passive systems.

The two systems can be used in the same greenhouse - but not at the same time. Negative systems require restricted air intake openings to achieve air flow speed. Because of this, open vents or sidewalls make exhaust fans almost completely ineffective.

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greenhouse light dep
Timer Control for Light Dep
Price: $990.00 plus tax(es)

24 hour timer unit for roll up shade systems (Call for a quote) used to adjust the photo-period.
Allows for several openings and closings in a 24 hour period - the benefit is that the curtain can be automatically raised after the sun sets. CSA pre-approval (VEC-CSA) is available as an option.
control for roll up motor
Incremental Controller for Roll Up Motors (thermostat input)
Price: $980.00 plus tax(es)

Automate your roll up walls for a more consistent environment and crop.
Operates 2 roll up motors - they plug into any standard 110v. outlet. The motors are individually fused.
The incremental controllers energize every 10 minutes (adjustable), if the temperature is above the set point, the wall rises 6" (adjustable).
If the temperature is below the set point, the wall drops 6".
Limit switches on the motors determine the lower and upper travel of the motors.
Model VEC-TI is controlled with a thermostat (not supplied - see product code VETH)
CSA pre-approval (VEC-CSA) is available as an option.
greenhouse light dep
roll up motor, 156 nM
Price: $290.00 plus tax(es)

Use with a roll up wall up to 150.
Excellent reliability. Ideal for light deprivation and blackout systems.
24 volt DC motor, comes with built in limit switches. Torque: 156 Nm; RPM: 2.2; Amps: 4 max (7 amps max. load) Revolutions : 40 max; Weight: 4.6 kg. Comes with a coupler 1 3/8" roll up tube. Controllers not included.
greenhouse haf fan  HAF
12" Air Circulation Fan
Price: $275.00 plus tax(es)

Good air circulation creates temperature uniformity, reduces temperature stratification and promotes evaporation from the leaves (to lessen disease).
We offer Schaefer fans - engineered for high performance and longevity.  Air is thrown in a tight conical pattern, ideal for horizontal air flow (HAF) applications.  Two year limited warranty.
.1 HP, 115/230 volts (1.3/.65 amps) 1554 cubic feet of air per minute
Greenhouse shutter with motor
Motorized PVC Shutters, 12"
Price: $264.00 plus tax(es)

Motorized shutters can used for: air intakes for exhaust fans; or simply to let in fresh air.
12 5/8" X 12 5/8" rough opening.
Motor control (thermostat or computer) not supplied.
greenhouse light dep
roll up motor, 44 nM
Price: $198.00 plus tax(es)

Use with a roll up wall 100' or less.
Excellent reliability. Ideal for ventilation, light deprivation and blackout systems.
24 volt DC motor, comes with built in limit switches. Torque: 44 Nm RPM: 4.5 Amps: 2 (max: 4) Revolutions : 40 Weight: 3.5 Kg
Both couplers are used with 1-3/8" outside diameter tube.
We provide a list of items (available from a home building centre) necessary for install - or purchase installation kits. Controllers not included.
greenhouse vent, greenhouse shutter
Motor for Aluminium Shutter
Price: $197.00 plus tax(es)

Automate any shutter.
greenhouse vent, greenhouse shutter
Aluminium Shutter, 30"
Price: $182.00 plus tax(es)

Brushed aluminium.  Automate with shutter motors (requires a thermostat or other controller - not included ) or VEL thermal opener.
rough opening: 30 1/2" wide X 31"
aluminium tubelock
Price: $150.00 plus tax(es)
Call to arrange delivery.

120' per order (10 lengths of 12') + shipping
Call or email to arrange delivery.
Attach poly to tubes between 1 and 1-5/8" diameter.
Use with motorized roll up walls for light deprivation and blackout systems.
greenhouse light dep
Self-Lock, 5:1 Gear Cranks, Chain Pull
Price: $143.00 plus tax(es)

Gear cranks, 5:1, self locking, chain pull (20' of chain).  Can be used for:
- small runs of rack and pinion vents
- ridge roll up systems
- roll up vents in gutter houses.  Ideal for light deprivation and blackout systems.  Installation hardware sold separately, call for options.